When a driver looks aside or sleeps to fail to confirm a forward obstacle while driving, the vehicle might collide with the obstacle. To avoid such dangerous situations, developed is an automatic brake device that uses a vehicle-mounted radar or a camera to monitor an obstacle forward of the vehicle, and in a case where the travelling vehicle will potentially collide with the forward obstacle, actuates a brake of the vehicle.
In such an automatic brake device as described above, if the brake is actuated at an unnecessarily early timing after detection of an obstacle or the like, for example, a driver might erroneously recognize that the automatic brake device malfunctions. On the other hand, if the brake is actuated with a delay, the vehicle will potentially collide with the obstacle.
Thus, to start actuation of the brake at an appropriate timing after detection of an obstacle or the like, urgent braking by the automatic brake device is required to have further enhanced brake performance of automatic braking.
In a known technique, a booster circuit boosts electric power of a battery so that a charging circuit is charged with the boosted electric power, and the electric power of the charging circuit is supplied to an electric motor when necessary. In this manner, even in a case where a necessary motor output rapidly increases, such as the case of urgent avoidance or urgent braking, high responsiveness can be obtained (see, for example, Patent Document 1).